The infectivity of sexual spores of Histoplasma capsulatum was tested. Using 5 strains of H. capsulatum, effect of the cultural conditions on the preservation of sexual cycle in H. capsulatum was studied. The three new sterols from mutants of cryptococcus neoformans and Aspergillus fennelliae were identified. Strains of Sporothrix Schenckii were studied for their temperature tolerance in vitro and for the type of lesions they have produced in humans. Critical comparison was made between strains of S. Schenckii and Ceratocystis stenoceras.